wouldn't mind keepin track of how you go on this....
i plan on setting up my ke25 SR with rack as the 4age doesn't give the factory steering linkages enough room. 2tg i think has better room for it tho.
mark H from auckland originally used a ke35 x-member in his ke20 and cut/weld an ae86 rack onto it. he didn't get the angles quite right so it went out of allignment when the car bounced, but the concept was there. just make sure the pivots for the tie rods are the same width as the pivots for the control arms and you should be sussed. also try get the pivots on the same horizontal plane so the steering angles don't get fuked up.
the column was a mix of ae86 shaft with ke20 case i think with a bit of cutting welding... probly illegal tho. the ke3 id imagine would be easier solution.
his improved version was a complete ae86 x-member and rack with the ends of the x-member shortened and modified to fit the ke20 chassis. this way the pivot points are as they came from factory. ke2 and ke3 apparently have the same width x-member mounting points but the bolts are wider apart nth/sth on the ke3 so slotting will make it fit. ke70/ae86 have wider x-member hence the shortening required.
let us know how ya get on